The present invention relates to an electromechanical apparatus for producing an axial force for the actuation of a clamping device, preferably of a chuck that rotates with the spindle or arbor for a machining tool. The apparatus includes an electric motor that has a stator and a rotor, with the relative movement between the rotor and the stator being transferable, via a gear system and a shaft drive, as an axial movement, to a tie rod, which is preferably hollow.
Apparatus of the aforementioned general type, especially for actuating chucks that rotate with the arbor of a machining tool, are known. With the apparatus disclosed in German Offenlegungsschrift No. 31 01 301, a central shaft is used that is connected to the tie rod. Especially in view of the hollow configuration of the tie rod, this shaft has to have a large thread diameter and hence large thread dimensions, so that not only do heavy structures result, but in addition, due to the high frictional forces, a particularly large electric motor must also be used. Furthermore, a complicated process for the production of the movement results, since the gears that are connected to the rotor of the electric motor in a planetary fashion have different numbers of teeth because these gears on the one hand ride in a fixed gear ring, and on the other hand ride in a rotatably mounted double gear that in turn is provided with the toothing that acts as the nut.
Starting from an apparatus of the aforementioned general type, it is an object of the present invention to reduce not only the space required but also the weight, and at the same time, to reduce the frictional losses, to simplify the construction so that the inventive electromechanical apparatus can also be used with today's turning machines, that customarily operate at high speeds and with high clamping forces.